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当 FTP 库下仅列出 iso.gz 时，wget 如何能够下载 iso 文件

tag-icon • tag-icon ftp iso-image wget solaris gz
当 FTP 库下仅列出 iso.gz 时，wget 如何能够下载 iso 文件

我从 FTP 服务器（URL：ftp://foo.com/bar/...) 这对我来说很陌生。您能给我提供一些文档或解释一下以下内容是如何实现的吗？

如果我使用 wget 获取文件夹的 URL，我会得到一个index.html（显示在帖子底部）以下列表，表明只有压缩文件可用：os_image_123_0-incr-repo.iso.gz

我可以通过 wget 获取此文件的 URL，然后我将得到一个带有特定 MD5 校验和的 gzip 文件。

c4fd702b3ad296561b2ec7e4b888e624  os_image_123_0-incr-repo.iso.gz
os_image_123_0-incr-repo.iso.gz:        gzip compressed data - deflate method , original file name

但是我也可以通过 wget 获取相同的文件 URL，省略.gz扩展名，只留下文件名os_image_123_0-incr-repo.iso，现在我将得到一个 iso 文件，该文件未在index.html.

08daf88aca95325c3aa9ae6406e02198  os_image_123_0-incr-repo.iso
os_image_123_0-incr-repo.iso:   ISO 9660 filesystem image

就好像 wget“知道”从 iso.gz 文件中提取 iso。

这是怎么回事？它是如何运作的？

index.html这是文件夹中列出的内容：

2016 Apr 13 14:45  Directory   <a href="ftp://foo.com/bar/05/.RE/">.RE/</a> 
2016 Apr 13 14:36  File        <a href="ftp://foo.com/bar/05/README.11.3.7">README.11.3.7</a>  (3097 bytes)
2016 Apr 13 14:36  File        <a href="ftp://foo.com/bar/05/md5sum-repo-iso-123_0.txt">md5sum-repo-iso-123_0.txt</a>  (63 bytes)
2016 Apr 13 13:02  File        <a href="ftp://foo.com/bar/05/md5sums.txt">md5sums.txt</a>  (321 bytes)
2016 Apr 13 09:52  File        <a href="ftp://foo.com/bar/05/os_image_123_0-ai-sparc.iso">os_image_123_0-ai-sparc.iso</a>  (570142720 bytes)
2016 Apr 13 09:53  File        <a href="ftp://foo.com/bar/05/os_image_123_0-ai-x86.iso">os_image_123_0-ai-x86.iso</a>  (496521216 bytes)
2016 Apr 13 13:02  File        <a href="ftp://foo.com/bar/05/os_image_123_0-fallback_boot-sparc.pkg">os_image_123_0-fallback_boot-sparc.pkg</a>  (103859114 bytes)
2016 Apr 13 14:37  File        <a href="ftp://foo.com/bar/05/os_image_123_0-incr-repo.iso.gz">os_image_123_0-incr-repo.iso.gz</a>  (3613854717 bytes)
2016 Apr 13 09:52  File        <a href="ftp://foo.com/bar/05/os_image_123_0-text-sparc.iso">os_image_123_0-text-sparc.iso</a>  (885370880 bytes)
2016 Apr 13 09:53  File        <a href="ftp://foo.com/bar/05/os_image_123_0-text-x86.iso">os_image_123_0-text-x86.iso</a>  (795648000 bytes)
2016 Apr 13 14:38  Directory   <a href="ftp://foo.com/bar/05/zipped-repo/">zipped-repo/</a>

添加 wget 输出。

[my_user 503 0 /tmp]$ wget ftp://foo.bar.com/products/Solaris_11/s11.3/support/sru07/05/sol-11_3_7_5_0-incr-repo.iso.gz
--2016-05-10 06:39:19--  ftp://foo.bar.com/products/Solaris_11/s11.3/support/sru07/05/sol-11_3_7_5_0-incr-repo.iso.gz
           => ‘sol-11_3_7_5_0-incr-repo.iso.gz’
           Resolving foo.bar.com (foo.bar.com)... 10.10.11.11
           Connecting to foo.bar.com (foo.bar.com)|10.10.11.11|:21... connected.
           Logging in as anonymous ... Logged in!
           ==> SYST ... done.    ==> PWD ... done.
           ==> TYPE I ... done.  ==> CWD (1) /products/Solaris_11/s11.3/support/sru07/05 ... done.
           ==> SIZE sol-11_3_7_5_0-incr-repo.iso.gz ... 3613854717
           ==> PASV ... done.    ==> RETR sol-11_3_7_5_0-incr-repo.iso.gz ... done.
           Length: 3613854717 (3.4G) (unauthoritative)

           sol-11_3_7_5_0-incr-repo.iso.gz        100%[===========================================================================>]   3.37G  99.5MB/

           2016-05-10 06:39:56 (94.4 MB/s) - ‘sol-11_3_7_5_0-incr-repo.iso.gz’ saved [3613854717]

[my_user 505 0 /tmp]$ wget ftp://foo.bar.com/products/Solaris_11/s11.3/support/sru07/05/sol-11_3_7_5_0-incr-repo.iso
--2016-05-10 06:43:25--  ftp://foo.bar.com/products/Solaris_11/s11.3/support/sru07/05/sol-11_3_7_5_0-incr-repo.iso
           => ‘sol-11_3_7_5_0-incr-repo.iso’
           Resolving foo.bar.com (foo.bar.com)... 10.10.11.11
           Connecting to foo.bar.com (foo.bar.com)|10.10.11.11|:21... connected.
           Logging in as anonymous ... Logged in!
           ==> SYST ... done.    ==> PWD ... done.
           ==> TYPE I ... done.  ==> CWD (1) /products/Solaris_11/s11.3/support/sru07/05 ... done.
           ==> SIZE sol-11_3_7_5_0-incr-repo.iso ... done.

           ==> PASV ... done.    ==> RETR sol-11_3_7_5_0-incr-repo.iso ... done.

           sol-11_3_7_5_0-incr-repo.iso               [                                                            <=>             ]   4.04G  32.3MB/

           2016-05-10 06:45:39 (30.9 MB/s) - ‘sol-11_3_7_5_0-incr-repo.iso’ saved [4337887232]

答案1

很可能服务器被配置为查找.gz文件，当未找到请求的文件时，返回提取的内容。

mod_rewrite使用 HTTP，使用 Apache和模块进行设置可能很容易mod_deflate。不确定某些 FTP 服务器是否支持此功能。

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